
Alvin Meyer Liberman,
whose ideas set the agenda for fifty years of
research in the psychology of speech and laid the ground for modern
computer speech synthesis, died on January 13th [2000] at a hospital in
Mansfield, Connecticut. Dr. Liberman, former President and Director
of Research at Haskins Laboratories in New Haven, Professor Emeritus
of Psychology at the University of Connecticut and of Linguistics at
Yale University, was 82. He died of complications following open
heart surgery.
The goal of his early work, sponsored by the Veterans'
Administration after World War II, was to develop the sound output
of a reading machine for the blind, a device that would scan print
and produce a distinctive acoustic pattern for each
letter of the alphabet. Despite years of effort, Dr. Liberman and
his colleagues at Haskins Laboratories never succeeded in devising
an acoustic array that listeners could follow faster than Morse
code, roughly 1/10 of a normal speaking rate, and intolerably slow
for extended use.
This failure raised the question to which Dr. Liberman devoted much
of the rest of his research life: Why is speech so much faster and
more efficient as a carrier of linguistic information than other
sounds? The answer gradually emerged from dozens of experiments in
the 50s and 60s.
Speech is not an arbitrary signal that just happened to be available
as language evolved; rather, speech is an integral part of language.
Consonants and vowels, the discrete phonemic elements essential for
a sizeable lexicon, do not combine like beads on a string, but are
overlapped, or encoded, into syllables; speed is thus purchased at
the price of complexity. Human listeners are biologically adapted to
decode the continuously variable signal of running speech and to
recover its discrete phonemic components.
In the course of developing this answer, Dr. Liberman and his
colleagues discovered many of the main acoustic cues to the
consonants and vowels of English. These cues later served to guide
the development of artificial speech synthesis, now widely used for
machine to human communication.
Dr. Liberman's provocative work was largely responsible for drawing
speech into the mainstream of experimental cognitive psychology,
where his "nativist" views were not to everyone's liking. But he
thrived on controversy, and up until the last months of his life he
maintained a steady stream of ingenious and telling experiments to
support what he liked to call his "unconventional view" against the
"conventional view" of most other experimental psychologists.
During the 70s and 80s, Dr. Liberman increasingly collaborated with
his wife, the late Dr. Isabelle Yoffe Liberman, and other Haskins
scientists on reading. A central discovery of this work was that
children who have difficulty in learning to read almost always lack
what Isabelle Liberman termed "phoneme awareness": they cannot
easily learn to break a word into its component consonants and
vowels. The critical requirement of phoneme awareness for learning
to read alphabetic print is now internationally recognized, in large
part due to the two Libermans' passionate advocacy of the
"alphabetic principle" against the "whole word," or "sight reading"
method of instruction.
Alvin Liberman was a member of the National Academy of Sciences and
of the American Academy of Arts and Sciences, a Fellow of the
American Psychological Assocation and of the Acoustical Society of
America. He also received many other awards, including the Warren
Medal from the Society of Experimental Psychologists; honorary
doctoral degrees from the State University of New York and from the
Universite Libre de Bruxelles, and a medal from the College de France,
Paris.
He is survived by two sons, Mark of Ardmore, Pennsylvania, and Charles of
Milton, Massachusetts; by a daughter, Sarah Ash, of Raleigh, North
Carolina, and by nine grandchildren.
(This obituary was written by Michael Studdert-Kennedy.)
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